[tauntdesigns]

Hi Group,

I've put off building this lathe long enough. I bought most of the stuff over 2 years ago (life Happens) and I ended up doing a kit conversion of my mill first.

I can no longer put it off and will start with post/thread here, that way I'll have to finish it. I actually started making chips 10 days ago BUT, I'm real sloooow..

Here's a few pictures: 8x14, Z-axis solid model assembly, and what i've got done so far.

Did I mention, I'm real slow,
Jack

P.S. I hope this is the right place for this thread

[ckm]

Hi Group,

I've put off building this lathe long enough. I bought most of the stuff over 2 years ago (life Happens) and I ended up doing a kit conversion of my mill first.

I can no longer put it off and will start with post/thread here, that way I'll have to finish it. I actually started making chips 10 days ago BUT, I'm real sloooow..

Here's a few pictures: 8x14, Z-axis solid model assembly, and what i've got done so far.

Did I mention, I'm real slow,
Jack

P.S. I hope this is the right place for this thread

Cool! I've been waiting for someone to do this and document it.... I understand about the slow part, I have the same thing.

Chris.

[tauntdesigns]

Well I guess I'll go out and saw up some material for the lower carriage (where the hand wheel and half nut lever are). I think my design on it is a good one, not much to it.

I'm not totally sold on my nut block design, although I believe it'll work just fine. I can't make up my mind on a 2 surface mounting block or a 1 surface mount.

Pic of the model of the carriage and ball nut block (2 surface mounting).

[ckm]

This would be to replace the half-nut? Are you retaining the acme screw or replace it with a ballscrew?

What I did on my 7x10 was remove the underside of the carriage and replace it with an aluminum block. The block was drilled through to accept the ballscrew nut, which was also flanged. However, this removed any hope of ever using the lathe manually, which was OK as I just used an MPG.

Chris.

[tauntdesigns]

Chris,

Yes, I'm replacing the stock acme with a ballscrew. I removed the whole underside of the carriage (hand wheel, half nut, lever, and the cast iron housing). I making everything out of 6061 al, the big block replaces the cast iron housing, and the little block will be threaded to accept the ballnut.

Yeah, I'll only be able to control it through the computer, but that's OK I'll just use a MPG, MDI, or do little short op programs. Everything I'm making for it is being done on a cnc'd X3 in little one op programs. Right now, I'm writing them by hand (pen&paper) and typing them into an editor (notepad). That's part of the reason I'm so slow (brain gettin' old).

Well, I better get back outside and start squaring up the block I sawed then, drill and tap some holes. The sooner I finish the Z-axis, the sooner I can start pulling my hair out over what to do about the cross slide (major ball nut clearance problem).

Later,
Jack

[ckm]

That's basically what I did, except I left the acme screw on the cross slide due to the clearance issue. Someone said you could get 8mm ballscrews, which would work but would likely cost a fortune...

Chris.

[tauntdesigns]

It's not the size of the ballscrews that is a problem it's the size of the ballnut that will not fit under the slide. Of course if you go small enough on the screw, it may have a smaller nut.

I've got a couple of ideas;
Nut mounted either on the front of the slide, or back of the slide. If mounted front side you lose travel, if mounted to the back you end up having alot of ballscrew sticking out the back.

Mount the screw to the side of the slide, mounting the nut to the side of the slide.

Or maybe machine a new slide out of cast iron. If I do away with the compound slide, I could machine a slide that was thick enough to machine a tunnel big enough to clear the nut mounted underneath it.

As slow as I am, I got time to think about it,
Jack

[tauntdesigns]

:withstupi
(nuts)
Have you ever went to the saw with the wrong dimension written down? I DID
What's bad is, I didn't notice until a bunch of mill work was done :withstupi ROOKIE! uugggg

While I was doing the milling (bad piece), I was thinking of other designs for the ballnut holder, which would also change the piece I was milling on. Now, I get that chance.

Oh well, back to the saw with the right dimension. Of course now I have to order more material to do the cross slide................

Jack

[tauntdesigns]

I feeling better about my little error,

All the mounting holes (clearance for bolts) are way over-sized. I was afraid that they needed to be that way in order to fit the parts to the machine...... I happy to say the threaded holes are much better.
I drilled my clearance holes much closer to size (.010" over instead of .100" over). I bolted the bearing blocks to the machine, put a travel indicator on the carriage/saddle and aligned/level the motor bearing block and set the zero. I then went down to the other bearing block to check how close it was to being on zero. It was plus .003" with out doing anything to it, other then bolting it up.
THAT's A lot closer then I thought it would be.

Cross slide:
I'm leaning towards putting the ballnut on the backside of the slide.............

Jack

[tauntdesigns]

The stormy weather has stopped and I have finished the re-design of the carriage/saddle assembly SO, I'll be cutting metal again tonight. I also ordered some more material to replace my oops :withstupi from the other nite. I also ordered some carbide lathe tools for turning the ballscrew.

Here's are a couple of pictures of the design I came up with. One exploded view and one assembled.

Any feedback (nuts) is welcome,
Jack

[MRM RCModels]

Just signing on. Like your work.

[tauntdesigns]

Welcome, and Thanks.

I have to say, I like yours too.. Watching your build on the X3, with all the solid models, has inspired me to dust off the old Pro/E software and start my Lathe build.

How's your build going?

I'm waiting on an order of carbide lathe tools to come in, then I can start turning down the ballscrews. I also have ordered material for the X-axis(cross slide axis) motor mount and the cross slide ball nut block.

Later,
Jack

[MRM RCModels]

Welcome, and Thanks.

I have to say, I like yours too.. Watching your build on the X3, with all the solid models, has inspired me to dust off the old Pro/E software and start my Lathe build.

How's your build going?

Later,
Jack

Thanks. My build is going really slow. I have recieved almost all of my parts except the ones I really need (nuts). Hopefully they'll come in this weekend.....

[tauntdesigns]

Update:

I got the lathe tools, so I got no excuse for not starting on the ball screws. I'll have to tear down the lathe of the new parts and put it back like it was for turning the screws. I've got a 5c lathe chuck that I've never used, I thinking about using it for the screws.........

I finished the x-axis extension block. I changed the mounting some (carriage side), I added 2 more holes to make it more rigid. On the bearing/motor mount side I used the same hole pattern as the Nema23 motors. Did I say it was finished, oops, I still need to either cut a 1.5 dia. pocket or a 1.5 dia. boss for locating the next assembly......

I also have finished the front half of the lower carriage block.....

I tapped the 15/16th hole for the ballnut. It went easier then I thought it would! The ballnut is designed to sit down in the mounting block 1.200". I bored a hole .008" bigger then the major diameter of the tap 1.200" deep. I then bored the tap drill size thru the rest of the part. The top bore helped align the tap to get started straight, plus I used a center point in the end of the tap. When I was done they're were no witness marks on the top bore, so I'm pretty sure it went in straight (as least within .004").....

[tauntdesigns]

I finished the Z-axis ballnut mounting block (bad picture).

I tried to cut the ballscrew on my bandsaw...lol I took it to the grinder first and ground down below the threads and then took it to the bandsaw. The poor saw didn't even make a mark on the screw. I'll just grind all the way through.

I mounted a 5c chuck and indicated it in (within .0006"). I'm hoping the chuck will hold it without marring the threads. After mounting the chuck I noticed that I had just turned a 8x14 lathe into a 8x10 lathe. Lost a few inches travel.........

[tauntdesigns]

I've been a little slow the last few days. I took the 5c chuck off, after getting it indicated in I realized I needed to make a bushing to go in the pulley side of the spindle to keep the ballscrew from whipping around. I also found that the ballscrew's diameter was .612" and the collect I had was .625". That might have been close enough, but I decided to use the 5" 3-jaw that I used to make the bushing. I also made another bushing and sawed through the side of it and used it at the jaw side to keep from marring the ballscrew.

I didn't use a grinder to remove the threaded area of the screw. I just slowly cut away at the screw with a brazed carbide lathe tool. On the first screw, I would set a depth and let it cut the full length. The screw would get really hot, towards the end of the screw, it may have annealed it's self, but towards the shoulder it became work hardened.(pain in the butt)

On the second screw, I took small bites on the diameter for about 1/4" length at a time until I removed the thread the length of the cut. The screw didn't get near as hot, but it did take 3 regrinds of the tool.

I tried to use a threading die, I couldn't get it to start straight no matter how I tried. So, I finished putting the machine back together so I could use the leadscrew for threading. I changed the gears around so I could get a metric thread and went after it. Once I got close I chased the thread with the threading die. (worked great).

The cut to the shoulder: I made it a little long and worked (held) my dimensions back to the end and then faced the end to get ride of the center used for the tailstock center. I hope that made sense.......

Next:
Spacers to go in between the angular bearings on the motor side.
Bearing retainers
X-axis bearing/motor mount
X-axis ballnut block
Then wait on the New Gecko G540 to come out

I know the G540 is a 4-axis set-up.... I have a few reasons for this.
1) If a drive fails, I just change the motor cable to one of the other drives and change settings in Mach3 and continue on.
2) If I do something wrong setting them up and let the magic smoke out, I'll have another chance to get it right........
3) 2 G203v's is $300.00 plus a BOB for $100.00...... Projected cost of the G540 is around $300.00 and has a built-in BOB plus 2 extra drives.

Til' next time,
Jack
P.S. I had a picture of the thread but had too much light on it and my piece of junk camera didn't like it.

[tauntdesigns]

If I worked for me..... I'd fire me!!!!

When I put the 5" 3-jaw chuck on the lathe, after indicating it in, I didn't get the bolts fully tight. The bolts were real snug, but not tight. Didn't notice it until after turning the threads...urrrrgh%$#*&. It had moved .002" which is .004" run-out.

I had left the cross slide ballscrew twice as long as it needed to be (just hadn't cut it to length yet... Lucky me ). I can cut the end off of the z-screw, re-thread it and cut it to length for the cross slide. The one I hadn't cut to length yet is still long enough to be the z-axis screw.

Just to see how a ballscrew that was out .002" acted on the machine.... I torn apart the lathe (again) and mounted the z-axis.

Wow, everything spins freely. (could I have gotten both ends off the same direction?)

I mounted the motor and coupler......... everything fit nicely.

The motor and screw should have fit nicely, because the bearing journal, threads, and coupler journal were all turned at the same time. I'm guessing that if a problem shows up, it will be between the ballnut/mount and the screw (which will see .004" runout).

WHAT TO DO? WHAT TO DO? WHAT TO DO?

Oh Well,
Jack

[tauntdesigns]

After doing things around the house the past week, I finally got back to working on the conversion.

Well, nobody talked me into leaving the ballscrews the way they are, so I'll be re-doing them Sunday.

I finished the x-axis bearing/motor mount Friday nite. Saturday is for making the slide ballnut plate and drill and tap the slide for the nut plate. After I redo the screws, I should be done with the mechanical part.

Pics Saturday or Sunday,
Jack

[tauntdesigns]

Didn't get as much done today as I thought I would (nuts)....... Oh well!

more pics:

Later,
Jack

[tauntdesigns]

I bought some 2" OD polycarbonate tubing for use as the x-axis ballnut/ballscrew chip cover. I cut a boss around the threads in the slide/ballnut plate. I can then mount the tubing to the boss.

While looking the lathe and thinking about what I was going to do about a cover for the z-axis. I started looking at the bearing retaining rings on the bearing blocks of the z-axis. I realized I could make a cut-out (slot) in some tubing for the ballnut to fit though and mount the tube ends around the bearing retainer rings.

I got a question:
Can you heat-form polycarbonate tubing or is it already set?
I'd like to form a flange on the ends of the tube.

Later,
Jack